Digit Replantation Practice: A Comparison of Three Rat Models

Digit replantation is a complex surgery that nearly always needs to be done as an emergency. As such it is often difficult to teach. Several models have been developed to train surgeons in this procedure. We compare three rat models of replantation with the aim of ascertaining which most simulates the digit replantation. Inbred albino rats were selected and divided into three groups of 13 each, tail, penile, and hind replant groups. Three rats in each group were anesthetized, the specific amputation injury is created and is replanted for the anatomic component of the study. For the comparative section, 10 animals were anesthesized and the amputated parts were replanted under standard conditions. The parameters measured included weight, vessels and nerve diameters, method of fixation, total ischemia and replant times, the patency rates (after operation and at one week post surgery), as well as postoperative complications. All rats survived in the procedure. There was patency in all groups immediately. Rat tail group had 90%, penile group 100%, and hind limb group 90% survival 1 week after the replantation. There was one mortality in the hind limb group. The penile replant group was the shortest (p < 0.001), and all vessel sizes were comparable except the central artery of the tail which was significantly smaller (p < 0.001). The processes of the hind limb group most simulated the human digit replant procedure, though the ischemia and total replant times are significantly longer (p < 0.005). Though the immediate and 1 week patency rates were similar in all three groups, the hind limb replantation model involved steps most similar to human digit replant surgery and is recommended as the preferred teaching model.

Successful Microsurgical Replantation of Scalp Amputation Using Medicinal and Chemical Leech Therapy: A Case Report

Scalp amputation is a very rare occurrence worldwide. In particular, replantation failure may occur from venous congestion, which represents a major complication of replantation. Accordingly, this study reports on a scalp amputation case with successful replantation treatment using medicinal and chemical leech therapy. On November 11, 2017, a 47-year-old female patient experienced a complete amputation injury starting from the top of the nose involving the total scalp by rolling machine that packs laundry. Severe venous congestion was controlled by medicinal leech therapy performed six times a day and chemical leech therapy (subcutaneous low-molecular-weight heparin injection) three times a day for 10 days. Approximately 85% of the scalp was replanted, and hair growth was confirmed. The basic concept of replantation surgery, “replace tissue with like tissue,” makes replacement impossible with tissues other than the hair-bearing scalp. Accordingly, the authors present a case of successful replantation with both medicinal and chemical leech therapy.

Integrative Analysis of Axolotl Gene Expression Data From Regenerative and Wound Healing Limb Tissues

ABSTRACTAxolotl (Ambystoma mexicanum) is a urodele amphibian endowed with remarkable regenerative capacities manifested in scarless wound healing and full restoration of amputated limbs. Several regenerative cues of the axolotl limb were successfully unraveled due to the advent of high-throughput technologies and their employment in tackling research questions on several OMICS levels. The field of regenerative biology and medicine has therefore utilized the axolotl as a major and powerful experimental model. Studies which have previously unraveled differentially expressed (DE) genes en masse in different phases of the axolotl limb regeneration have primarily used microarrays and RNA-Seq technologies. However, as different labs are conducting such experiments, sufficient consistency may be lacking due to statistical limitations arising from limited number of sample replicates as well as possible differences in study designs. This study, therefore, aims to bridge such gaps by performing an integrative analysis of publicly available microarray and RNA-Seq data from axolotl limb samples having comparable study designs. Three biological groups were conceived for the analysis; homeostatic tissues (control group), from amputation/injury timepoint up to around 50 hours post amputation (wound healing group), and from 50 hours to 28 days post amputation/injury (regenerative group). Integrative analysis was separately carried out on the selected microarray and RNA-Seq data from axolotl limb samples using the “merging” method. Differential expression analysis was separately implemented on the processed data from both technologies using the R/Bioconductor “limma” package. A total of 1254 genes (adjusted P < 0.01) were found DE in regenerative samples compared to the control, out of which 351 showed magnitudes of Log Fold Changes (LogFC) > 1 and were identified as the top DE genes from data of both technologies. Downstream analyses illustrated consistent correlations of the logFCs of DE genes distributed among the biological comparisons, within and between both technologies. Gene ontology annotations demonstrated concordance with the literature on the biological process involved in the axolotl limb regeneration. qPCR analysis validated the observed gene expression level differences between regenerative and control samples for a set of five genes. Future studies may benefit from the utilized concept and approach for enhanced statistical power and robust discovery of biomarkers of regeneration.

Functional Outcomes of Antegrade Homodigital Neurovascular Island Flaps for Fingertip Amputation

Background: Fingertip amputations can be debilitating and challenging to treat, due to the need for both function and cosmesis. We studied the functional outcomes of patients receiving an antegrade homodigital neurovascular island flap for fingertip amputations. Methods: From 2004 to 2013, we performed 13 cases of antegrade homodigital neurovascular island flaps. Functional outcomes were studied. Four had Allen Zone II and nine had Zone III injuries. Seven were performed as secondary surgery. The mean followup period was 36 weeks. Results: All the flaps survived. Ten of 11 had less than or equal to 6 mm two-point discrimination. Five patients were noted to have mild flexion contracture at distal interphalangeal joints ranging from 5 to 10 degrees. There were three cases with nail deformity, three with fingertip hypersensitivity and four with cold intolerance. For patients injured on duty, the mean duration of sick leave taken was 18.5 weeks. Conclusions: With careful patient selection, the antegrade homodigital neurovascular island flap is a reliable means of restoring the function of the fingertip after amputation injury with significant tissue loss. Flap survival, sensibility and mobile adjacent joint can be expected, even when performed as a secondary surgery and for patients with work-related injuries.